The shipment of pallet loads of goods constitutes a substantial part of commercial traffic. Frequently the pallet loads may comprise articles that do not stack in sufficiently stable configurations to permit stability during shipping. Often it is desirable to ship pallet loads of goods which are dimensionally different in size and shape from load to load depending on the purchase orders being filled. In these situations and numerous others, it has been found desirable to have some means for wrapping the pallet load with a membrane such as plastic film or fabric or plastic netting that will tightly fit about the articles in the load and contain them during the bumps and knocks of commercial transport.
Perhaps the most common of these methods comprises turning the pallet load while leading the ribbon of film onto the load and permitting it to wrap the load as the pallet turns. In some methods, the wrapping may be followed by heating of the membrane to shrink fit it about the goods, in other cases, an elastic membrane is wrapped under tension to obtain a tight fit. Examples of the prior art are found in U.S. Pat. No. 3,867,806, entitled "Process of Making a Stretch-Wrap Package" which issued to Lantech, Inc. on Feb. 25, 1975; U.S. Pat. No. 3,896,288 entitled "Method of Heat-Shrink Wrapping Goods" which issued to Martin J. Tulkoff on July 22, 1975.
The apparatus which has been developed and sold to implement this method of pallet wrapping suffers the common deficiency that the pallet load must be rotated during wrapping. Accordingly, means must be provided to get the pallet load onto and off of a rotatable table and means must be provided to rotate and support the table under a variety of loads and conditions. It is perceived by the present inventor that this deficiency leads to increased costs of fabrication, installation and operation for such apparatus.
Other apparatus have been developed which rotate both the pallet load and the source of the wrapping membrane, for example that disclosed in C.P. 1,114,279 entitled "Tension Wrap Packaging Machine" which issued to Stretch-Wrap Inc. on Dec. 15, 1981. However, this apparatus is again complicated and would seem to suffer all of the deficiencies mentioned above. See also in this regard, U.S. Pat. No. 4,079,565 entitled "Stretch-Wrapped Package, Process and Apparatus" which issued to Lantech, Inc. on Mar. 21, 1978.
Other apparatus is disclosed in U.S. Pat. No. 3,793,798 entitled "Shrink Palletized Process and Apparatus" which issued to Lantech, Inc on Feb. 26, 1974, which teaches a dispenser mounted on an arm which rotates over a palletized load to wrap the load with plastic membrane. After wrapping, the palletized load is carried on into an oven for heat shrinkage. The apparatus described in this patent uses a roll of membrane material having sufficient width to wrap a package of goods on a pallet with a single turn of the membrane roll about the palletized load. This apparatus lacks versatility for wrapping loads having a variety of heights. Accommodation is made for loads of differing heights by having apparatus which will permit the insertion of different size rolls on the dispenser. However, this apparatus suffers the deficiency that where each load is of a different height it would require constant changing of the rolls in order to complete coverage without wastage of material.